While the process of mass spectral interpretation for FAB and FAB MS/MS (CAD) spectra is still in its infancy relative to that in place for EI mass spectra, more data are available when FAB is used than MALDI. The goal is to understand how MS/MS spectra for MALDI generated ions compare to those generated by FAB. Are the fragment ions observed essentially the same for both methods, or are there obvious differences from a comparison of the m/z values alone? Are there dramatic differences in the relative intensities of the fragment ions generated in these two experiments, or do the most stable fragment ions dominate in both? Can mass spectral interpretation approaches that are being used for FAB/CAD spectra be used as a starting point for MALDI/PSD spectra? In this project, the targeted analytes are cardiac glycosides. These compounds were selected because they have molecular weights below 2,000, and are highly functionalized molecules that have been previously studied by a number of methods. Positive and negative ion spectra are being collected and compared from both experiments. From these, similarities will be defined and differences investigated, to provide a context in which fragmentation of MALDI-generated ions can be defined.